Compressor unloader and check valve unit

ABSTRACT

An improved compressor unloader and check valve unit normally operable automatically to unload a compressor when the pressure downstream from the compressor exceeds a predetermined value and having means for locking it in either its loaded or unloaded mode of operation.

ll 0 j] v time States Patent 1 1 1 3,7 Krechel Jan. 22, 1974 [54] COMPRESSOR UNLOADER AND CHECK 1,088,667 2/1914 Snell 251/112 X VALVE U I 7 2,970,609 2/1961 Beremand 251/112 X 1,196,862 9/1916 Hayes 137/523 n e tor: Joseph L.- Krechel, 1420 Hanley 2,474,772 6/1946 Ashton... 137/115 Industrial CL, Chesterfield, Mo. 3,071,153 1/1963 Cornelius... 137/523 X 63144 3,367,622 2/1968 Moore 251/114 [22] Filed: Aug. 28, 1972 Primary qm i iylllli xa131,9 1? PP N03 ,101 Aitiir r ii figeh t, or F irm Koenig, Senniger, Powers and Leavitt [52] US. Cl ..137/1l6,137/118, 137/119,

251/115 [57] ABSTRACT [51] Int. Cl. G05d 16/10 [58] Field of Search 137/115, 116 H8 H9 523; An improved compressor unloader and check valve 25 I 11 1 14 1 15 112 unit normally operable automatically to unload a compressor when the pressure downstream from the com- [56] References Cited pressor exceeds a predetermined value and having means for locking it in either its loaded or unloaded UNITED STATES PATENTS mode of operation 3,587,619 6/1971 Krechel 137/116 8 Claims, 6 Drawing Figures COMPRESSOR UNLOADER AND CHECK VALVE UNIT BACKGROUND OF THE INVENTION This invention relates to an improvement ina compressor unloader and check valve unit, such as is shown in my US. Pat. No. 3,587,619, for unloading a compressor (i.e., to permit it to free wheel) when the system pressure downstream from the compressor exceeds a predetermined value, the valve unit either being operable in response to system pressure automatically to unload the compressor or manually operable to unload the compressor, the improvement involving means for alternatively locking the valve unit in its loaded or unloaded mode of operation.

SUMMARY OF THE INVENTION Among the several objects of this invention may be noted the provision of an improved unloader and check valve unit, such as above described for a compressor or the like, which may be operated (either automatically or manually) to unload the compressor, or which may be selectively locked in either its loaded or unloaded mode of operation; and the provision of such an unloader valve unit having relatively simply and inexpensive means for selectively locking it in either its loaded or unloaded mode of operation. Other objects and features of this invention will be in part apparent and in part pointed out hereinafter.

In general, an unloader valve unit of this invention fora compressor has an inlet port for connection of a line from the compressor, an outlet port, an exhaust port, and valve means responsive to pressure at the outlet port and acting upon increase in pressure at the outlet port above a predetermined value to open up communication between the inlet and exhausts ports. This valve means acts to block communication between the inlet and exhaust ports when this pressure is below the predetermined value. It includes a member movable between a first position in which the valve means is in a first or loaded mode of operation blocking communication between the inlet and exhaust ports and a second position in which the valve means is in a second or unloaded mode of operation opening up communication between the inlet and exhaust ports for unloading the compressor. The member has means for manually moving it from its first to its second position, and means for alternatively locking it in its first or second position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective of an improved unloader and check valve unit of this invention showing a locking hail of the unit in a retracted position;

FIG. 2 is an enlarged longitudinal cross-sectional view of the unit with the bail (shown in phantom) in a locking position;

FIG. 3 is a perspective view of the unit showing the bail in its locking position;

FIG. 4 is an enlarged partial longitudinal crosssection of the unit with parts in the position as shown in FIG. 3;

FIG. 5 is a plan view of the bail member; and

FIG. 6 is an elevation view of the bail member.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, an improved unloader and check valve unit of this invention, as indicated in its entirety at 1, is shown to comprise a valve body 3 having an inlet port 5, and outlet port 7 and an exhaust port 9. The inlet port is adapted to be connected to the outlet of an air compressor and the outlet port is adapted to be connected to a pneumatic load, such as an accumulator, which is to be supplied with compressed air from the compressor. The various ports are interconnected within the valve body via a passage or bore 11. At 13 is generally indicated vent valve means including a vent valve member 15 responsive to pressure at the outlet port 7 and acting in response to increase in pressure at outlet port 7 above a predetermined value to open up communication between the inlet and exhaust ports, and acting to block communication between these ports when said pressure is below said predetermined value. The valve member 15 is movable between the closed position shown in FIG. 2 in which the unloader valve unit is in its loaded mode of operation with communication blocked between the inlet and exhaust ports for supplying compressed air from the compressor to the pneumatic load and an open position in which the unloader valve unit is in its unloaded mode of operation such that there is communication between the inlet and exhaust ports for venting compressed air to the atmosphere thereby to unload the compressor. Valve member 15 is engageable with valve seat 17 formed by a shoulder in bore 11.

On the opposite side of the exhaust port 9 from valve seat 17 is a cylinder 19 of larger cross-section than valve seat 17. Vent valve means 13 also includes a piston 21 reciprocally mounted within the cylinder and interconnected with valve member 15 by a piston rod 23 so that increase in pressure within the cylinder at the outer end of the cylinder causes the valve member to move from its closed to its open position for unloading the compressor. The piston is fitted with a seal 25 to seal against the wall of the cylinder. A coil compression spring 27 surrounds the piston rod and reacts from a shoulder 28 in cylinder 19 biasing valve member 15 toward the closed position in which it seats against its valve seat 17 thereby to block exhaust port 9 from the remainder of the system.

The portion of cylinder 19 adjacent the outer or free end of piston 21 constitutes a pressure chamber, as indicated at 29. A control passage 31 places this pressure chamber in communication with a bleed passage generally indicated at 33 and with a passage 35 in communication with outlet port 7. Vent valve means 13 further includes a pilot valve assembly generally indicated at 37. This pilot valve assembly includes a pilot valve ball member 39 engageable with a valve seat 41 and an axially movable member or rod 42 for resiliently holding the ball seated against valve seat 37 to block communication between passage 35 and pressure chamber 29. Pilot valve assembly 37 further includes a lower fitting 43 threaded in a bore 45 in valve body 3 and an upper fitting 47 threaded in a bore 49 in the lower fitting. Fitting 43 carries an O-ring 51 in an annular groove at its lower end to seal bore 45 from passage 31. Fitting 47 has an axial bore 53 therethrough in communication with bore 49 in the lower fitting.

Rod 42 is carried within the bores 49 and 53 in fittings 43 and 47, respectively, and it carries a flanged cap 57 on its bottom end. This cap has a loose fit within bore 49 at the bottom end of the lower fitting 43 and is adapted to bear against ball 39. Rod 42 and cap 57 each have a loose fit within their respective bores in fittings 43 and 47 to provide the bleed passage 33 for permitting pressure within chamber 29 to bleed to the atmoshpere. Rod 42 is movable from a first position (FIG. 2) in which cap 57 is in engagement with ball 39 for holding the ball seated against valve seat 41 and blocking communication between passage 35 and pressure chamber 29 and a second or retracted position in which the ball is free to move from its valve seat opening up communication between passage 35 and chamber 29. With the rod in its first position, pressure in chamber 29 bleeds to the atmoshpere via bleed 33 so as to permit spring 27 to bias valve member 15 to its closed position blocking communication between inlet port and exhaust port 9, and with the rod in its second position the ball 39 blocks bleed 33 and pressure in passage 35 enters chamber 29 and acts against piston 21 thereby to move valve from its closed to its open position opening up communication between the inlet and exhaust ports thereby to unload the compressor.

A coil compression spring 59 surrounds rod 42 and biases the rod toward its first position for seating ball 39 on its seat 41. Spring 59 holds rod 42 in its first position and holds the ball seated against its valve seat until pressure in passage 35 exceeds a predetermined value which is sufficient to overcome the force exerted on the ball by the rod and the spring. As ball 39 is pushed upwardly from its seat, it moves into engagement with the bottom end of fitting 43 adjacent bore 49 therein closing communication between chamber 29 and the bleed passage 33 allowing pressure in the chamber to increase thus moving valve member 15 from its closed to its open position. The predetermined pressure at which ball 39 is forced from its valve seat may be varied by screwing fitting 47 into or out of the bore 49 in fitting 43 to vary the compression of spring 59.

Rod 42 extends from fitting 47 and has a finger-grip ring 61 of wire wound in a closed loop with overlapping ends inserted through a diametric hole in the outer end of the rod. This grip ring enables the rod to be readily gripped for manually moving it (pulling it out) against the bias of spring 59 from its first position (FIG. 2) to its second position (FIG. 4). With the rod in its second position, ball 39 is free to move from its valve seat and open up communication between passage 35 and chamber 29.

A check valve member 63 is slidably mounted in body 3 for movement between a closed position (not shown) engaging a seat 65 and thereby blocking communication between inlet port 5 and outlet port 7, and an open position permitting communication therebetween, as shown in FIG. 2. A spring 67 biases the check valve member 63 toward its closed position. As shown, the spring 67 reacts from the left end of body 3, which may be formed by a heat 68 threaded in the valve body. Because spring 67 biases check valve member 63 into its closed position from the outlet port pressure as communicated back through the outlet port assists spring 67 in biasing valve member 63 into its closed position.

In accordance with this invention, means is provided for alternatively locking rod 42 down in its stated first position (FIG. 2) or up in its stated second position (FIG. 4). This means comprises a locking member constituted by a wire bail 69 pivotally mounted on the valve body 3 for swinging movement between a retracted position clear of the rod 42 (see FIG. 1 and the solid line position of the bail in FIG. 2) into engagement with the rod (more particularly the finger grip 61 on the rod) alternately to hold the rod down against movement up away from its first position (as shown in phantom in FIG. 2) or to hold the rod up in its second position and against movement down to its first position (see FIG. 4). When the rod 42 is locked down (FIG. 2), the ball 39 is locked down on its seat so that the valve unit is locked in its loaded mode of operation. When the rod 42 is locked up (FIG. 4), the ball is free to open and the valve unit is, in effect, locked in its unloaded mode of operation.

The bail 69 is made of relatively stiff wire generally in U-shape having spaced apart leg 71 and a central receiving clip 73 in the form of a loop between and integral with the legs. This clip or loop is adapted to receive, straddle and resiliently grip the upper portion of rod 42 when the bail member is in either its first or second locking position. The bottom end of each of the legs is bent inwardly, as indicated at 75, and is sprung into a blind hole 77 in valve body 3. Thus, the ball is mounted so that it may be readily swung between its retracted and locking positions. Clip 73 is formed by bending the wire, as indicated at 79, to extend generally at right angles from the plane of the U-shaped portion of the bail and by bending the wire approximately 180 on itself, as indicated at 81. The clip 73 is stepped, as indicated at 83 in FIG. 4., forming a first or front portion constituting a high step H having a recess or pocket 85 and a second or rear portion consitituting a low step L having another pocket 87. The high step H of the clip is spaced from the blind holes 77 in the valve body a distance somewhat greater than the low step L of the clip. In FIG. 5, pockets 85 and 87 are show to be of somewhat larger cross section in plan than the distance between the right angle bends 79 so that as the bail is swung to lock rod 42 and as the clip is pushed onto the rod, the sides of the clip are sprung apart. As the rod is received in either the first or second pocket, the clip springs back to its original shape and the rod is resiliently gripped by the clip and held captive within one of the pockets in such manner that vibration and movement of the valve unit will not inadvertently move the locking member from its locking position.

With rod 42 in its first position in which it resiliently holds ball 39 against its seat 41 and with bail 69 in the FIG. 2 locking position, the portion of rod 42 above grip ring 61 is held captive within pocket 87 in the lowstep rear portion of the clip with the lower surface of the clip bearing down against the grip ring thereby to lock the rod in its first position. With the rod so received in rear pocket 87 and with grip ring 61 bearing against the bottom surface of the low-step L, bail 69 substantially prevents any upward movement of rod 42 and thus the valve unit is locked in its loaded mode of operation. Alternatively, with the rod in its second position and with the bail in its second locking position (see FIGS. 3 and 4), the portion of the rod below the grip ring is held captive within pocket 85 in the high step H of clip 73 with the grip ring in engagement with the upper surface of the clip so that the rod under the bias of spring 59 is prevented from returning to its lowered position. Thus, the valve unit is, in effect, locked in its unloaded mode of operation.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In an unloader valve for a compressor having an inlet port for connection of a line from the compressor, an outlet port, an exhaust port, valve means responsive to pressure at the outlet port and acting upon increase in said pressure above a predetermined value to open up communication between the inlet and the exhaust ports, said valve means acting to block communication between the inlet and exhaust ports when said pressure is below said predetermined value, said valve means including a member movable between a first position in which the valve means is in a first mode blocking communication between the inlet and exhaust ports, and a second position in which the valve means is in a second mode opening up communication between the inlet and exhaust ports for unloading the compressor, said member having means for manually moving it from its first to its second position, and means for alternatively locking said member only in either its first or in its second position.

2. In an unloader valve as set forth in claim 1, said locking means being carried by said unloader valve for movement between a retracted position clear of said member into engagement with said member alternatively either to hold said member against movement away from its first position or to hold said member against movement from its second to its first position.

3. In an unloader valve as set forth in claim 2, said means for manually moving said member comprising a finger grip, and said locking means being engageable with said grip.

4. In an unloader valve as set forth in claim 3, said member comprising a rod extending out of the unloader valve axially movable between its said first and second positions and biased toward its first position, said finger grip being adjacent the outer end of said rod.

5. In an unloader valve as set forth in claim 4, said rod being biased inwardly toward its said first position, said locking means being alternately engageable over said finger grip to hold the rod in its first position, or under the finger grip after the rod has been pulled out to its second position to hold the rod in its second position.

6. In an unloader valve as set forth in claim 5, said locking means comprising a bail formed of wire pivotally mounted on the unloader valve for swinging movement from a retracted position clear of the rod into position wherein a portion of the bail is either over or under said grip.

7. In an unloader valve as set forth in claim 6, said portion of the bail being in the form of a loop adapted to straddle the rod either over or under said grip.

8. In an unloader valve as set forth in claim 7, said loop having a high step for engagement under said grip and a low step for engagement over said grip. 

1. In an unloader valve for a compressor having an inlet port for connection of a line from the compressor, an outlet port, an exhaust port, valve means responsive to pressure at the outlet port and acting upon increase in said pressure above a predetermined value to open up communication between the inlet and the exhaust ports, said valve means acting to block communication between the inlet and exhaust ports when said pressure is below said predetermined value, said valve means including a member movable between a first position in which the valve means is in a first mode blocking communication between the inlet and exhaust ports, and a second position in which the valve means is in a second mode opening up communication between the inlet and exhaust ports for unloading the compressor, said member having means for manually moving it from its first to its second position, and means for alternatively locKing said member only in either its first or in its second position.
 2. In an unloader valve as set forth in claim 1, said locking means being carried by said unloader valve for movement between a retracted position clear of said member into engagement with said member alternatively either to hold said member against movement away from its first position or to hold said member against movement from its second to its first position.
 3. In an unloader valve as set forth in claim 2, said means for manually moving said member comprising a finger grip, and said locking means being engageable with said grip.
 4. In an unloader valve as set forth in claim 3, said member comprising a rod extending out of the unloader valve axially movable between its said first and second positions and biased toward its first position, said finger grip being adjacent the outer end of said rod.
 5. In an unloader valve as set forth in claim 4, said rod being biased inwardly toward its said first position, said locking means being alternately engageable over said finger grip to hold the rod in its first position, or under the finger grip after the rod has been pulled out to its second position to hold the rod in its second position.
 6. In an unloader valve as set forth in claim 5, said locking means comprising a bail formed of wire pivotally mounted on the unloader valve for swinging movement from a retracted position clear of the rod into position wherein a portion of the bail is either over or under said grip.
 7. In an unloader valve as set forth in claim 6, said portion of the bail being in the form of a loop adapted to straddle the rod either over or under said grip.
 8. In an unloader valve as set forth in claim 7, said loop having a high step for engagement under said grip and a low step for engagement over said grip. 